const AsyncHTTP = @This();

request: ?picohttp.Request = null,
response: ?picohttp.Response = null,
request_headers: Headers.Entry.List = .empty,
response_headers: Headers.Entry.List = .empty,
response_buffer: *MutableString,
request_body: HTTPRequestBody = .{ .bytes = "" },
allocator: std.mem.Allocator,
request_header_buf: string = "",
method: Method = Method.GET,
url: URL,
http_proxy: ?URL = null,
real: ?*AsyncHTTP = null,
next: ?*AsyncHTTP = null,

task: ThreadPool.Task = ThreadPool.Task{ .callback = &startAsyncHTTP },
result_callback: HTTPClientResult.Callback = undefined,

redirected: bool = false,

response_encoding: Encoding = Encoding.identity,
verbose: HTTPVerboseLevel = .none,

client: HTTPClient = undefined,
waitingDeffered: bool = false,
finalized: bool = false,
err: ?anyerror = null,
async_http_id: u32 = 0,

state: AtomicState = AtomicState.init(State.pending),
elapsed: u64 = 0,
gzip_elapsed: u64 = 0,

signals: Signals = .{},

pub var active_requests_count = std.atomic.Value(usize).init(0);
pub var max_simultaneous_requests = std.atomic.Value(usize).init(256);

pub fn loadEnv(allocator: std.mem.Allocator, logger: *Log, env: *DotEnv.Loader) void {
    if (env.get("BUN_CONFIG_MAX_HTTP_REQUESTS")) |max_http_requests| {
        const max = std.fmt.parseInt(u16, max_http_requests, 10) catch {
            logger.addErrorFmt(
                null,
                Loc.Empty,
                allocator,
                "BUN_CONFIG_MAX_HTTP_REQUESTS value \"{s}\" is not a valid integer between 1 and 65535",
                .{max_http_requests},
            ) catch unreachable;
            return;
        };
        if (max == 0) {
            logger.addWarningFmt(
                null,
                Loc.Empty,
                allocator,
                "BUN_CONFIG_MAX_HTTP_REQUESTS value must be a number between 1 and 65535",
                .{},
            ) catch unreachable;
            return;
        }
        AsyncHTTP.max_simultaneous_requests.store(max, .monotonic);
    }
}

pub fn signalHeaderProgress(this: *AsyncHTTP) void {
    var progress = this.signals.header_progress orelse return;
    progress.store(true, .release);
}

pub fn enableBodyStreaming(this: *AsyncHTTP) void {
    var stream = this.signals.body_streaming orelse return;
    stream.store(true, .release);
}

pub fn clearData(this: *AsyncHTTP) void {
    this.response_headers.deinit(this.allocator);
    this.response_headers = .{};
    this.request = null;
    this.response = null;
    this.client.unix_socket_path.deinit();
    this.client.unix_socket_path = jsc.ZigString.Slice.empty;
}

pub const State = enum(u32) {
    pending = 0,
    scheduled = 1,
    sending = 2,
    success = 3,
    fail = 4,
};
const AtomicState = std.atomic.Value(State);

pub const Options = struct {
    http_proxy: ?URL = null,
    hostname: ?[]u8 = null,
    signals: ?Signals = null,
    unix_socket_path: ?jsc.ZigString.Slice = null,
    disable_timeout: ?bool = null,
    verbose: ?HTTPVerboseLevel = null,
    disable_keepalive: ?bool = null,
    disable_decompression: ?bool = null,
    reject_unauthorized: ?bool = null,
    tls_props: ?*SSLConfig = null,
};

const Preconnect = struct {
    async_http: AsyncHTTP,
    response_buffer: MutableString,
    url: bun.URL,
    is_url_owned: bool,

    pub const new = bun.TrivialNew(@This());

    pub fn onResult(this: *Preconnect, _: *AsyncHTTP, _: HTTPClientResult) void {
        this.response_buffer.deinit();
        this.async_http.clearData();
        this.async_http.client.deinit();
        if (this.is_url_owned) {
            bun.default_allocator.free(this.url.href);
        }

        bun.destroy(this);
    }
};

pub fn preconnect(
    url: URL,
    is_url_owned: bool,
) void {
    if (!FeatureFlags.is_fetch_preconnect_supported) {
        if (is_url_owned) {
            bun.default_allocator.free(url.href);
        }

        return;
    }

    var this = Preconnect.new(.{
        .async_http = undefined,
        .response_buffer = MutableString{ .allocator = bun.http.default_allocator, .list = .{} },
        .url = url,
        .is_url_owned = is_url_owned,
    });

    this.async_http = AsyncHTTP.init(bun.default_allocator, .GET, url, .{}, "", &this.response_buffer, "", HTTPClientResult.Callback.New(*Preconnect, Preconnect.onResult).init(this), .manual, .{});
    this.async_http.client.flags.is_preconnect_only = true;

    bun.http.http_thread.schedule(Batch.from(&this.async_http.task));
}

pub fn init(
    allocator: std.mem.Allocator,
    method: Method,
    url: URL,
    headers: Headers.Entry.List,
    headers_buf: string,
    response_buffer: *MutableString,
    request_body: []const u8,
    callback: HTTPClientResult.Callback,
    redirect_type: FetchRedirect,
    options: Options,
) AsyncHTTP {
    var this = AsyncHTTP{
        .allocator = allocator,
        .url = url,
        .method = method,
        .request_headers = headers,
        .request_header_buf = headers_buf,
        .request_body = .{ .bytes = request_body },
        .response_buffer = response_buffer,
        .result_callback = callback,
        .http_proxy = options.http_proxy,
        .signals = options.signals orelse .{},
        .async_http_id = if (options.signals != null and options.signals.?.aborted != null) bun.http.async_http_id_monotonic.fetchAdd(1, .monotonic) else 0,
    };

    this.client = .{
        .allocator = allocator,
        .method = method,
        .url = url,
        .header_entries = headers,
        .header_buf = headers_buf,
        .hostname = options.hostname,
        .signals = options.signals orelse this.signals,
        .async_http_id = this.async_http_id,
        .http_proxy = this.http_proxy,
        .redirect_type = redirect_type,
    };
    if (options.unix_socket_path) |val| {
        assert(this.client.unix_socket_path.length() == 0);
        this.client.unix_socket_path = val;
    }
    if (options.disable_timeout) |val| {
        this.client.flags.disable_timeout = val;
    }
    if (options.verbose) |val| {
        this.client.verbose = val;
    }
    if (options.disable_decompression) |val| {
        this.client.flags.disable_decompression = val;
    }
    if (options.disable_keepalive) |val| {
        this.client.flags.disable_keepalive = val;
    }
    if (options.reject_unauthorized) |val| {
        this.client.flags.reject_unauthorized = val;
    }
    if (options.tls_props) |val| {
        this.client.tls_props = val;
    }

    if (options.http_proxy) |proxy| {
        // Username between 0 and 4096 chars
        if (proxy.username.len > 0 and proxy.username.len < 4096) {
            // Password between 0 and 4096 chars
            if (proxy.password.len > 0 and proxy.password.len < 4096) {
                // decode password
                var password_buffer = std.mem.zeroes([4096]u8);
                var password_stream = std.io.fixedBufferStream(&password_buffer);
                const password_writer = password_stream.writer();
                const PassWriter = @TypeOf(password_writer);
                const password_len = PercentEncoding.decode(PassWriter, password_writer, proxy.password) catch {
                    // Invalid proxy authorization
                    return this;
                };
                const password = password_buffer[0..password_len];

                // Decode username
                var username_buffer = std.mem.zeroes([4096]u8);
                var username_stream = std.io.fixedBufferStream(&username_buffer);
                const username_writer = username_stream.writer();
                const UserWriter = @TypeOf(username_writer);
                const username_len = PercentEncoding.decode(UserWriter, username_writer, proxy.username) catch {
                    // Invalid proxy authorization
                    return this;
                };
                const username = username_buffer[0..username_len];

                // concat user and password
                const auth = std.fmt.allocPrint(allocator, "{s}:{s}", .{ username, password }) catch unreachable;
                defer allocator.free(auth);
                const size = std.base64.standard.Encoder.calcSize(auth.len);
                var buf = this.allocator.alloc(u8, size + "Basic ".len) catch unreachable;
                const encoded = std.base64.url_safe.Encoder.encode(buf["Basic ".len..], auth);
                buf[0.."Basic ".len].* = "Basic ".*;
                this.client.proxy_authorization = buf[0 .. "Basic ".len + encoded.len];
            } else {
                //Decode username
                var username_buffer = std.mem.zeroes([4096]u8);
                var username_stream = std.io.fixedBufferStream(&username_buffer);
                const username_writer = username_stream.writer();
                const UserWriter = @TypeOf(username_writer);
                const username_len = PercentEncoding.decode(UserWriter, username_writer, proxy.username) catch {
                    // Invalid proxy authorization
                    return this;
                };
                const username = username_buffer[0..username_len];

                // only use user
                const size = std.base64.standard.Encoder.calcSize(username_len);
                var buf = allocator.alloc(u8, size + "Basic ".len) catch unreachable;
                const encoded = std.base64.url_safe.Encoder.encode(buf["Basic ".len..], username);
                buf[0.."Basic ".len].* = "Basic ".*;
                this.client.proxy_authorization = buf[0 .. "Basic ".len + encoded.len];
            }
        }
    }
    return this;
}

pub fn initSync(
    allocator: std.mem.Allocator,
    method: Method,
    url: URL,
    headers: Headers.Entry.List,
    headers_buf: string,
    response_buffer: *MutableString,
    request_body: []const u8,
    http_proxy: ?URL,
    hostname: ?[]u8,
    redirect_type: FetchRedirect,
) AsyncHTTP {
    return @This().init(
        allocator,
        method,
        url,
        headers,
        headers_buf,
        response_buffer,
        request_body,
        undefined,
        redirect_type,
        .{
            .http_proxy = http_proxy,
            .hostname = hostname,
        },
    );
}

fn reset(this: *AsyncHTTP) !void {
    const aborted = this.client.aborted;
    this.client = try HTTPClient.init(this.allocator, this.method, this.client.url, this.client.header_entries, this.client.header_buf, aborted);
    this.client.http_proxy = this.http_proxy;

    if (this.http_proxy) |proxy| {
        //TODO: need to understand how is possible to reuse Proxy with TSL, so disable keepalive if url is HTTPS
        this.client.flags.disable_keepalive = this.url.isHTTPS();
        // Username between 0 and 4096 chars
        if (proxy.username.len > 0 and proxy.username.len < 4096) {
            // Password between 0 and 4096 chars
            if (proxy.password.len > 0 and proxy.password.len < 4096) {
                // decode password
                var password_buffer = std.mem.zeroes([4096]u8);
                var password_stream = std.io.fixedBufferStream(&password_buffer);
                const password_writer = password_stream.writer();
                const PassWriter = @TypeOf(password_writer);
                const password_len = PercentEncoding.decode(PassWriter, password_writer, proxy.password) catch {
                    // Invalid proxy authorization
                    return this;
                };
                const password = password_buffer[0..password_len];

                // Decode username
                var username_buffer = std.mem.zeroes([4096]u8);
                var username_stream = std.io.fixedBufferStream(&username_buffer);
                const username_writer = username_stream.writer();
                const UserWriter = @TypeOf(username_writer);
                const username_len = PercentEncoding.decode(UserWriter, username_writer, proxy.username) catch {
                    // Invalid proxy authorization
                    return this;
                };

                const username = username_buffer[0..username_len];

                // concat user and password
                const auth = std.fmt.allocPrint(this.allocator, "{s}:{s}", .{ username, password }) catch unreachable;
                defer this.allocator.free(auth);
                const size = std.base64.standard.Encoder.calcSize(auth.len);
                var buf = this.allocator.alloc(u8, size + "Basic ".len) catch unreachable;
                const encoded = std.base64.url_safe.Encoder.encode(buf["Basic ".len..], auth);
                buf[0.."Basic ".len].* = "Basic ".*;
                this.client.proxy_authorization = buf[0 .. "Basic ".len + encoded.len];
            } else {
                //Decode username
                var username_buffer = std.mem.zeroes([4096]u8);
                var username_stream = std.io.fixedBufferStream(&username_buffer);
                const username_writer = username_stream.writer();
                const UserWriter = @TypeOf(username_writer);
                const username_len = PercentEncoding.decode(UserWriter, username_writer, proxy.username) catch {
                    // Invalid proxy authorization
                    return this;
                };
                const username = username_buffer[0..username_len];

                // only use user
                const size = std.base64.standard.Encoder.calcSize(username_len);
                var buf = this.allocator.alloc(u8, size + "Basic ".len) catch unreachable;
                const encoded = std.base64.url_safe.Encoder.encode(buf["Basic ".len..], username);
                buf[0.."Basic ".len].* = "Basic ".*;
                this.client.proxy_authorization = buf[0 .. "Basic ".len + encoded.len];
            }
        }
    }
}

pub fn schedule(this: *AsyncHTTP, _: std.mem.Allocator, batch: *ThreadPool.Batch) void {
    this.state.store(.scheduled, .monotonic);
    batch.push(ThreadPool.Batch.from(&this.task));
}

fn sendSyncCallback(this: *SingleHTTPChannel, async_http: *AsyncHTTP, result: HTTPClientResult) void {
    async_http.real.?.* = async_http.*;
    async_http.real.?.response_buffer = async_http.response_buffer;
    this.channel.writeItem(result) catch unreachable;
}

pub fn sendSync(this: *AsyncHTTP) anyerror!picohttp.Response {
    HTTPThread.init(&.{});

    var ctx = try bun.default_allocator.create(SingleHTTPChannel);
    ctx.* = SingleHTTPChannel.init();
    this.result_callback = HTTPClientResult.Callback.New(
        *SingleHTTPChannel,
        sendSyncCallback,
    ).init(ctx);

    var batch = bun.ThreadPool.Batch{};
    this.schedule(bun.default_allocator, &batch);
    bun.http.http_thread.schedule(batch);

    const result = ctx.channel.readItem() catch unreachable;
    if (result.fail) |err| {
        return err;
    }
    assert(result.metadata != null);
    return result.metadata.?.response;
}

pub fn onAsyncHTTPCallback(this: *AsyncHTTP, async_http: *AsyncHTTP, result: HTTPClientResult) void {
    assert(this.real != null);

    var callback = this.result_callback;
    this.elapsed = bun.http.http_thread.timer.read() -| this.elapsed;

    // TODO: this condition seems wrong: if we started with a non-default value, we might
    // report a redirect even if none happened
    this.redirected = this.client.flags.redirected;
    if (result.isSuccess()) {
        this.err = null;
        if (result.metadata) |metadata| {
            this.response = metadata.response;
        }
        this.state.store(.success, .monotonic);
    } else {
        this.err = result.fail;
        this.response = null;
        this.state.store(State.fail, .monotonic);
    }

    if (comptime Environment.enable_logs) {
        if (bun.http.socket_async_http_abort_tracker.count() > 0) {
            log("bun.http.socket_async_http_abort_tracker count: {d}", .{bun.http.socket_async_http_abort_tracker.count()});
        }
    }

    if (bun.http.socket_async_http_abort_tracker.capacity() > 10_000 and bun.http.socket_async_http_abort_tracker.count() < 100) {
        bun.http.socket_async_http_abort_tracker.shrinkAndFree(bun.http.socket_async_http_abort_tracker.count());
    }

    if (result.has_more) {
        callback.function(callback.ctx, async_http, result);
    } else {
        {
            this.client.deinit();
            var threadlocal_http: *bun.http.ThreadlocalAsyncHTTP = @fieldParentPtr("async_http", async_http);
            defer threadlocal_http.deinit();
            log("onAsyncHTTPCallback: {any}", .{std.fmt.fmtDuration(this.elapsed)});
            callback.function(callback.ctx, async_http, result);
        }

        const active_requests = AsyncHTTP.active_requests_count.fetchSub(1, .monotonic);
        assert(active_requests > 0);
    }

    if (!bun.http.http_thread.queued_tasks.isEmpty() and AsyncHTTP.active_requests_count.load(.monotonic) < AsyncHTTP.max_simultaneous_requests.load(.monotonic)) {
        bun.http.http_thread.loop.loop.wakeup();
    }
}

pub fn startAsyncHTTP(task: *Task) void {
    var this: *AsyncHTTP = @fieldParentPtr("task", task);
    this.onStart();
}

pub fn onStart(this: *AsyncHTTP) void {
    _ = active_requests_count.fetchAdd(1, .monotonic);
    this.err = null;
    this.state.store(.sending, .monotonic);
    this.client.result_callback = HTTPClientResult.Callback.New(*AsyncHTTP, onAsyncHTTPCallback).init(
        this,
    );

    this.elapsed = bun.http.http_thread.timer.read();
    if (this.response_buffer.list.capacity == 0) {
        this.response_buffer.allocator = bun.http.default_allocator;
    }
    this.client.start(this.request_body, this.response_buffer);
}

const log = bun.Output.scoped(.AsyncHTTP, .visible);

const HTTPCallbackPair = .{ *AsyncHTTP, HTTPClientResult };
pub const HTTPChannel = Channel(HTTPCallbackPair, .{ .Static = 1000 });
// 32 pointers much cheaper than 1000 pointers
const SingleHTTPChannel = struct {
    const SingleHTTPCHannel_ = Channel(HTTPClientResult, .{ .Static = 8 });
    channel: SingleHTTPCHannel_,
    pub fn reset(_: *@This()) void {}
    pub fn init() SingleHTTPChannel {
        return SingleHTTPChannel{ .channel = SingleHTTPCHannel_.init() };
    }
};

pub const HTTPChannelContext = struct {
    http: AsyncHTTP = undefined,
    channel: *HTTPChannel,

    pub fn callback(data: HTTPCallbackPair) void {
        var this: *HTTPChannelContext = @fieldParentPtr("http", data.@"0");
        this.channel.writeItem(data) catch unreachable;
    }
};

const string = []const u8;

const DotEnv = @import("../env_loader.zig");
const HTTPThread = @import("./HTTPThread.zig");
const Headers = @import("./Headers.zig");
const std = @import("std");
const Encoding = @import("./Encoding.zig").Encoding;

const PercentEncoding = @import("../url.zig").PercentEncoding;
const URL = @import("../url.zig").URL;

const bun = @import("bun");
const Environment = bun.Environment;
const FeatureFlags = bun.FeatureFlags;
const MutableString = bun.MutableString;
const assert = bun.assert;
const jsc = bun.jsc;
const picohttp = bun.picohttp;
const Channel = bun.threading.Channel;
const SSLConfig = bun.api.server.ServerConfig.SSLConfig;

const ThreadPool = bun.ThreadPool;
const Batch = bun.ThreadPool.Batch;
const Task = ThreadPool.Task;

const HTTPClient = bun.http;
const FetchRedirect = HTTPClient.FetchRedirect;
const HTTPClientResult = HTTPClient.HTTPClientResult;
const HTTPRequestBody = HTTPClient.HTTPRequestBody;
const HTTPVerboseLevel = HTTPClient.HTTPVerboseLevel;
const Method = HTTPClient.Method;
const Signals = HTTPClient.Signals;

const Loc = bun.logger.Loc;
const Log = bun.logger.Log;